While I'm mostly in agreement with the majority opinion here, I want to play devil's advocate for a moment. If we are going to allow complete freedom on hire/fire, there are some potential consequences to consider.
Let's say Tyrell owns a soul food shop in Harlem, and he hires generic whitey JimmyJoeBob to work the grill. Let's assume that you can't taste any difference in the food Tyrell prepares versus the food JimmyJoeBob prepares. Now, one day, the customers notice that their soul food is being made by a white guy and they complain to Tyrell that such practice is wholly unacceptable and their business will go elsewhere until there's a proper brotha in the kitchen. (note- we now have a dollars-n-cents justification) Tyrell fires JJB, which is completely within his perogative in an "employment at will" legal structure, because JJB's skin color is having a negative impact on his business.
How's that gonna fly, folks? I intentionally reversed the roles so we don't have to address minority oppression, but imagine the shitstorm if the situation were the same but we're talking a grits-n-greens shop in Macon, Georgia and Tyrell was the one getting fired.